How DNS, IP addresses, and record types work: the core concepts behind every domain lookup, explained step by step.
Public vs. private address space
Public IP
192.0.2.10
globally unique -- routable from anywhere
Private ranges
not routable on the public internet
Your device has two addresses at once, and only one of them exists on the internet. Here is why, and what the reserved ranges mean.
Picking a TTL in practice
DNS TTL decides how fast your changes take effect. Learn what TTL means, how to look up a domain's TTL with dig, and which value to pick.
"Propagation" is really just caches expiring
0 min
you save the change
0-5 min
your DNS host updates
up to TTL
old answer still cached
after TTL
everyone sees the new one
Nothing is pushed anywhere -- each cache just stops reusing its copy
Nothing propagates anywhere. Understanding what actually happens during the wait tells you exactly how long it will take and how to shorten it.
A recursive DNS lookup, one hop at a time
Browser
wants example.com
Resolver
your ISP / 1.1.1.1
Root + TLD
who runs .com?
Authoritative
the real answer
Every hop down this chain is itself a DNS lookup, cached afterward
The single setting that decides which provider controls your DNS — and the reason your record edits sometimes have no effect at all.
The records you will meet in nearly every zone
The decision comes down to one question: do you control the IP address, or does someone else? Plus the root-domain rule that trips everyone up.
The records you will meet in nearly every zone
The record that actually points your domain at a server — its anatomy, the AAAA counterpart, and the four mistakes that break sites most often.
A recursive DNS lookup, one hop at a time
Browser
wants example.com
Resolver
your ISP / 1.1.1.1
Root + TLD
who runs .com?
Authoritative
the real answer
Every hop down this chain is itself a DNS lookup, cached afterward
What is the IP address of a website? Five ways to find the IP address of any website or URL, with exact commands for Windows, macOS, and Linux.
A recursive DNS lookup, one hop at a time
Browser
wants example.com
Resolver
your ISP / 1.1.1.1
Root + TLD
who runs .com?
Authoritative
the real answer
Every hop down this chain is itself a DNS lookup, cached afterward
The internet's phone book, traced end to end: what happens in the few milliseconds between typing a domain and the first packet reaching a server.
Two addressing schemes, running side by side
IPv4
192.0.2.10
32 bits -- ~4.3 billion addresses -- exhausted
IPv6
2606:4700::6810:84e5
128 bits -- 340 undecillion addresses
The numeric label behind every website, server, and phone on the internet — what it means, how to read it, and why there are two incompatible versions.
How an email finds your mail server
Sender
you@gmail.com
MX lookup
who takes mail?
Mail server
priority 10 first
Inbox
delivered
Lowest priority number wins; higher numbers are backups
MX records tell the internet which mail servers handle email for a domain -- and why they're structured differently from an A record.
Three layers share the name "DNS server"
Stub resolver
your own device
Recursive resolver
ISP, router, or 1.1.1.1
Authoritative
the domain's own DNS
Two very different jobs share the word 'DNS server' -- the recursive resolver that does the asking, and the authoritative server that has the answer.
Picking a TTL in practice
A domain's DNS time to live (TTL) controls how long an answer is cached before it's looked up again -- the real reason DNS changes don't appear everywhere instantly.